This page was always out of date so I have decided to just put a link here to the code pages on my "Instructables" website.

 

This describes how to build a basic Arduino controlled twin wheeler. 

 

Code is attached as .txt files to paste into Arduino sketches (or just view as text files).

 

There is an accel/gyro tester, a motor tester, a code example for a machine steered by a simple rocker switch and one steered by a potentiometer (thumb joystick of a Wii Nunchuck works well).

 

Link: